Manufacture of articles from cast-iron.



ALEXANDER E. QUTERBRIDGE, JR, or PHILADELPHIA, PENNS LVANIA,

MANUFACTURE. oF ARTICLES FROM CAST-IRON.

Specification of Letters- Patent,

Patented Feb. 5. 1 onv Application filed November 9, 1905. Serial No. 286.494.

To (LZ Z whom, it may concern: Be it known that I, ALEXANDER E. OUTER- BRIDGE, Jr. of No. 8 Summit avenue, in the whereof the followin is a specification.

-' made isto economicallyobtain the proper city of Philadelphia, county of Philadelphia, and State of Pennsylvania, have invented certain new and useful Improvements in the Manufacture of Articles from Cast Iron,

One of the diificu t problems of foundry practlce where miscellaneous castings are grades of iron fromone melt in a cupola suitable for different classes of castings requiring different qualities of. iron. "Thus the articles .circumstances it is the effort of the founder to vary as best he can the grade of metal in may range from castings of many tons weight usually of thick section requirin strong iron of close-grained texture often aving high chilling properties to small objects of a pound or so in'weight, frequently of thin sectrons, whichmay require to be machined, and therefore must be of softer metal having little or no tendency to chill. Under these thcupola'itself at different periods of heat and to so grou and: time his castings as to utilize to' the est advantage the different grades of 11011 which run'from the cupola in one continuous -melting operation. Even with the utmost care this practice is only apprroximately correct, since the. transition om one grade to another in the cupolais not absolutely ascertainable or, indeed, definite at all, and hence the effort has been to interpose between the period of the widelydifferent castings certain others, which are termed buffer-castings, as to Which intermediate or uncertain grades of iron can be used with comparative indiflerenee.

I have ascertained that by following the procedure about to be indicated I can produce in theladles themselves a great-variety of ades of iron with respect to hardness, chi ling properties, and other important characteristics, so that the general run of iron in the cupola need not be practically varied and may, moreover, beof what would be termed a low rade, the necessary treatment to control t e physical qualities being restricted to the relatively small quantity commonly used in a foundry-ladle and the changes within the desired limits being immediately attainable. By this means I am enabled to cast from the same cupola charge small articles, such as pulleys, with rims, say, one-quarter of an inch thick, soft enough to permit of machining and with negligible chillmg tendency, and heavy-castings having, if desired, high chilling properties and closegrained texture.

' In carrying out my process I proceed as follows: Imay melt in the cupola iron of character capable for'the castings of the lowgrained texture and high chilling propenies, and then tap into a ladle a charge suihcient for a partlc'ular casting or group of casimgs .est'grade to be made, which may have close which it is desired to make of softer iron having but little chilling tendency. I then combine with the molten metal in theladle a definite amount of a silicon compound in such form as'to be thoroughly and quickly difl'usib e and without attendant additions which W0 ld impair the desired result. For this purpose I prefer to use powdered ferrosilicon containing a large proportion of s1l1con'-say fifty per cent. of silicon-and I usually add it at the time of tapping of the metal into the ladle or soon thereafter in order to insure thorough combination. The casting is then poured in the usual manner.

Other ladl'es may be tapped from the same charge and treated with different quantities of ferrosilicon, depending upon the qualities desired for the ultimate product.

I have found that hard iron canbe modified so as to produce a relatively soft gray iron by the addition of even so little as one pound of fifty-per-cent. ferrosilicon to two hundred pounds of iron and that within certain limits the desired physical characteristics ofthe metal can be accurately controlled in correspondence with the percentage of the ,tained. If a low grade of ferrosilicon be added, (containing, say, only twenty per cent. of silicon,) the relatively large amount of iron contained in the addition tends not only to chill the contents of the ladle, but may in itself injuriously modify thev total .mass with relation to its intended purpose.

Moreover, under thesecircumstances the additioi1do(es not exhibit the immediate and thorough difl'usibility which characterizes the relatively high grade ferrosilicon and which is essential for the practical conduct of IOO IIC

I ingredients, but results either in'what may "teristic of moltenxcast-iron in the ladle in the operation, since it will be noted that the addition is made after the cessation of the actual melting process and that the reaction must be, effected during the periodwhen cooling is taking place. I

I have given the above proportions as typical of my invention, but do not wish to be understood as restricting myself thereto,

since they may be obviously modified to ob- 1 o tain the desiredgrade of cast-iron.

, I am of courseaware that it is not'broadly new to utilize ferrosilicon in'the manufacture of cast-iron, and I do not claim the same; but

so faras myexperience goes. in commercial practice theaddition has been made in the cupola itselfljwhichisnot only wasteful of the be considredas a fixed product orif varied during'theheat in a product which is inde- .20 terminate, 80-11mm to be predictable at. a

7 given moment ofta ping.

I am also aware t "at it has been suggested to employ silicon in its elemental form as an addition to cast-iron in' the'ladle. Careful 2 5' tests, however, have determined the fact that r the silicon thus designated is not dilfusible to any substantial extent in the cast-iron under the conditions characteristic of actual practice,and therefore will not produce the result 0 attained bymy process; I believe that the reason for this practical non-diilusibility is due to one or bothof two factorsviz., first, the high melting-point of the so-called elemental silicon, ,(or silicon not associated with such 'a vehicle as is. present when' ferrosilicon-is used,) and, second, the low specific gravity of such silicon. Whatever be the cause, I'have-found that at the temperature and under the conditions which are characnormalioundr'y practice and which are necessitated' bycommercial limitations the addition of such silicon does notproduce any ellicient or beneficial reaction which can be util- 4 5 'ized in the process of making castings. I

therefore no notclaim the use of the so-called elemental or practically pure silicon. I

such as the high-grade ferrosilicon above mentioned when added to a relatively small" quantity of melted cu Ola-iron, which has been withdrawnfrom't e source of heat-supply and its capacity when thus diffused-to produce definitely-controllable results in the physical characteristics which are essential in diiie'rent grades of castings.

The H 'ts'ofni -j'nveiition may be said for practical purposes to depend upon the characteristics that-the silicon com ound shall be readilydiifusible throughout t e metal in the ladle at the temperature normally employed at that stage of foundry practice and that the vehicle shall not substantially impair the resultant product. Such characteristics do notpractically exist when, on the one hand, the vehicle preponderates too greatly in the compound which is added, or, on the other hand, when it is present in such small percentage as not to substantially modify the indifiusible character of pure silicon at the temperature and under the conditions just mentioned.

Having thus'described my invention, 1 claim I The hereinbefore-described improvement in the manufacture of articles from cast-iron, which consists in diffusing throughout the metal in the ladle, after tapping, a silicon compound containing a relatively high percentage of silicon, and thereby modifying the grade of iron in the ladle itself, in accordance with the predetermined requirements of a' given casting, or group of castings.

In testimony whereof I have hereunto.

signed my name, at Philadelphia, Pennsylvania. this 8th day of November, 1905.

ALEXANDER E. OUTERBRIDGE, JR.

Witnesses:

JAMES H. BELL, E. L. FUL ERTON. 

